In order to assist customers in designing their storage layout for Exchange 2007, we have put together a calculator that focuses on driving the storage requirements (I/O performance and capacity) and what the optimal LUN layout should be based on a set of input factors.
You can download the calculator at http://msexchangeteam.com/attachment/432207.ashx
Note that the calculator does not make any recommendations toward storage design (RAID parity, number of disks, etc.), as the storage design is largely dependent on the type of storage array being utilized.
For more information on some basic requirements around storage design, see the following blog posts:
For more information about this calculator, see the following blog post: